Establishing the Principles of Compositional Design for Long Life Rail Steels

铁路轨道是一个复杂的相互联系的系统网络，其枢纽是轮轨之间的接触。因此，钢轨的劣化也是许多系统变量的函数，这一关键部件的成分设计和微观结构属性的优化需要基于对整个铁路网经历的应力状态范围的透彻了解和明确定义。正是在这一背景下，拟议的项目侧重于以下任务，这些任务的综合结果将使轨道钢的成分和微观结构设计得以优化，以实现所需的寿命和较低的寿命周期成本。冶金特性的表征：这将在各种钢轨钢上进行，无论是在原始状态下还是在受控测试之后。微观结构特征将包括诸如片层间距、板条厚度、渗碳体体积分数和渗碳体溶解的测量。建立全面的轮轨接触条件：钢轨所需的功能高度依赖于轨道和交通特性，因此即使在单一网络中，轮轨接触条件也可能有很大差异，从高速平坦线路的轮轨接触条件到客运和货运混合线路的紧凑曲线。将对过去广泛的研究结果进行整理，以确定在混合交通网络中可能遇到的接触条件的范围。受控实验室测试：对大直径双圆盘试验机进行了升级，使其能够开发出与赛道上遇到的接触条件类似的各种接触条件。将使用一种新的方法从商业上可用的轧制钢轨中提取样品。如有必要，将用定制成分的轧制板材补充这些板材。在严格控制的条件下，将建立各种可用的和新型钢轨钢的耐磨性和滚动接触疲劳的比较。以上分析的结果将被神经网络分析，以确定在受控试验下建立的各种成分元素对退化速率的影响。预期产量是优化钢轨钢成分的冶金设计规则，然后可以成为合理调整钢轨规格(如EN13674-1 2017)中钢轨成分的基础。

Railway track is a complex web of interconnected systems whose hub is the contact between wheel and rail. Consequently, degradation of rail is also a function of many system variables and the optimisation of the compositional design and microstructural attributes of this key component needs to be based on a thorough understanding and clear definition of the range of stress states experienced throughout a rail network. It is within this context that the proposed project is focused on the following tasks, the combined results of which will enable the optimisation of the compositional and microstructural design of rail steels to deliver the desired longevity and lower life cycle costs.1. Characterisation of metallurgical attributes: This will be undertaken on a wide range of rail steels both in the virgin and after controlled testing. Microstructural characterisation will include assessments such as measurement of interlamellar spacing, lath thickness, volume fraction cementite, and cementite dissolution.2. Establishing full range of wheel-rail contact conditions: The functionality required of the rail is highly dependent on the track and traffic characteristics and hence the wheel-rail contact conditions even within a single network can vary widely, from those for high-speed plain line to tight curves on mixed passenger and freight lines. Extensive past research results will be collated to define the range of contact conditions that could be encountered on a mixed traffic network3. Controlled laboratory tests: A large diameter twin disc test machine has been upgraded to enable development of a wide range of contact conditions that resemble those that are encountered in track. A novel methodology will be used to extract samples from commercially available rolled rails. These will be supplemented, if necessary, with rolled plates of bespoke compositions. Comparative resistance to wear and rolling contact fatigue will be established for the wide range of available and novel rail steels under closely controlled conditions.The results from the above analysis will be subjected to neural network analysis to establish the influence of the various compositional elements on the rate of degradation established under controlled testing. The expected output is a metallurgical design rule for the optimisation of rail steel compositions that could then form the basis for the rationalisation of compositions included in rail specifications, such as EN13674-1 2017.